Stewart



Aug. 9, 1955 s. STEWART 2,714,773

BLADE MECHANISM FOR ENDLESS TYPE DITCH DIGGER Filed Oct. 21, 1952 2Sheets-Sheet l (Ittorneg Aug. 9, 1955 s, STEWART 2,714,773

BLADE MECHANISM FOR ENDLESS TYPE DITCH DIGGER 3moentor 5/0/VEYSTEM/14197 United States Patent BLADE MECHANISM FOR ENDLESS TYPE DITCHBIGGER Sidney Stewart, Lincoln, Nehru, assignor of one-half to PetersonConstruction Company, Lincoln, Nebn, a corporation of NebraskaApplication October 21, 1952, Serial No. 315,914

3 Claims. (Cl. 37-86) line that is wider than the main wall portion ofthe foundation and provides a firm footing for the foundation. To obtainthis it is customary to dig the entire trench of the width of the baseand after the base is poured, to use a form of the proper width for thefoundation Wall disposed longitudinally in the trench and supportedabove the base region, thereby providing a foundation of invertedT-shape. The vacant space on each side of the wall portion of thefoundation is then filled in.

An object of this invention is to avoid the necessity for excavatingthis unused trench portion and for using forms for the pouring of theconcrete. More specifically an object is to excavate a trench which isinitially of the desired cross sectional shape with the relatively widebase and the wall portion of the trench above the base of the width ofthe foundation wall. Such a trench serves as its own form and theconcrete may be poured directly into it.

The invention therefore provides an apparatus which by a singlecontinuous operation makes an excavation that is of uniform widththroughout the wall portion and widens out at the bottom or baseportion. More particularly the invention provides means to cut anoutwardly flaring portion on each side along the bottom of the trench.

The invention is particularly applicable to tractor excavators employingtrailer excavating means of the bucket type operated by a chain on apivotally suspended boom. In accordance with the invention suitableflaring cutters are provided on the free end of the boom which areoscillated by a power take-off, preferably from the chain, and make anundercut along the bottom on each side of the trench. The buckets are inthe form of curved knives canted to constitute scoops which are disposedto collect the dirt removed by these flaring cutters and carry it outalong with the dirt removed from the intermediate region.

The invention also includes certain particular features of constructionand has other objects and advantages as will more particularly appearfrom the following description of the embodiment of the inventionillustrated in the accompanying drawings, in which Fig. 1 is a sideelevation of an apparatus embodying the invention;

Fig. 2 is a similar view on enlarged scale of the lower end portion ofthe boom as shown in Fig. 1 and illustrating the flaring knife and itsoperating means on one side;

Fig. 3 is an end View, partially in section, of the parts shown in Fig.2;

Fig. 4 is an illustration of the mechanism for driving 2,714,773Patented Aug. 9, 1955 the chain which carries the excavators and forraising and lowering the boom; and

Fig. 5 is a section through the finished trench containing thefoundation wall.

Fig. 1 shows a more or less conventional form of tractor excavator withthe improvements of this invention applied thereto. The tractor 1contains the usual power unit 2 for propelling the tractor and drivingthe excavating mechanism. The excavator in the form of a boom ispivotally suspended from the rear of the trailer its free end beingraised and lowered in the usual manner. The free end of the boom cutsits way into the earth to the desired depth of the trench and thedigging continues at that depth as the trailing excavating means aremoved along by the tractor.

The pivoted boom comprises an I-beam 3 which at its forward end ispivoted on a transverse shaft 4 extending between two suspension plates(one being shown) on the rear of the tractor and a sprocket chain 5which carries the excavators runs over a sprocket 6 on the shaft 4 atthe forward end of the beam and over an idler sprocket or roller 7 on abearing shaft 8 at the free or rear end of the beam. The means fordriving the sprocket 6 and for raising and lowering the beam are shownin Fig. 4.

The shaft 4 is an inner shaft and bears in a two part outer shaftcomprising the sections 9 and 10 which bear in fixed bearings 11 and 12,respectively. The two sections of the outer shaft are disposed onopposite sides of the sprocket 6 and this sprocket is fixed on the innershaft 4 which extends through the section 9 and has an extension beyondthe sprocket which bears in the inner end of the section 10 of the outershaft. A chain 13 driven by the power unit runs over a sprocket 14 onthe outer end of the inner shaft 4 and drives the sprocket 6 andexcavator chain 5.

The beam 3 is attached to the outer shaft sections 9 and 10 through twohub brackets 15 and 16 which are welded or otherwise secured to flangeson a bracket 17 which is also welded to outer shaft sections 9 and 10and has its flanges bolted to the web of the l-beam. The hub bracketshave hub portions which fit upon and are welded to the inner ends of theouter shaft sections 9 and 16 on opposite sides of the sprocket 6. Thusthe beam bears at its forward end upon the inner shaft 4 and in thefixed bearings 11 and 12.

The means for raising and lowering the boom are conventional and areshown only diagrammatically. A reversible motor (not shown) which isenergized from the tractor battery drives and idler sprocket 18 throughreduction gears in box 19 and this idler drives a leverage wheel 20which is bolted on the outer shaft section 10. Thus the boom is raisedor lowered at will merely by operating an appropriate switch for themotor circuit and the ratio of the reduction gears in the gear box isgreat enough to hold the boom rigid in any position.

The bearing shaft 8 and idler roller 7 are adjustable longitudinally ofthe beam 3 to control the tension of the chain 5. As shown, the bearingshaft 8 is mounted in the projecting ends of two adjustable plates 21and 22 disposed on opposite sides of the beam 3 and urged rearwardly byscrews 23 (one being shown) which are threaded in bosses Welded on thebeam faces and engage against the forward ends of the respective plates.These plates are shown as coupled by through bolts or rods, a slot inthe web of the beam permitting of the adjustment.

The chain 5 also runs over two intermediate idler sprockets (not shown)carried by adjustable brackets 24 and'25, respectively, on the beam 3,the one sprocket engaging the lower run of the chain and the other theupper run. As shown these sprockets carry screw scrapers 26 and 27respectively, on their shafts (one on each side of the trench) which areoperated by the sprockets in the proper directions to scrape away fromthe sides of the trench the earth deposited by the chain drivenexcavators. These screws are standard construction and form no part (ifthe invention. i

1' For excavating, the chain carries digging means Which herein arecalled scooping means and which are in the form of twosets of arcuateknives disposed slightly at an angle with their leading edges out. Theknives are arranged in right and left hand pairs, one set being thecenter knives 28 and cutting the center of the trench and the other set29 being outside the center knives and cutting the sides of the trench.In practice there are four pairs of center cut knives and nine pairs ofside cut knives, or twenty-six in all.

For the most part the mechanism above described is conventional. Theinvention resides in the means added thereto and combined therewith fordigging an outwardly flaring bottom to the trench coincidently with thedigging of the wall of the trench so that the excavation is made of thedesired cross section by a single continuous operation.

The flaring bottom to the trench is dug by a pair of flaring kniveswhich are pivotally mounted on the shaft 8 and are oscillated by powertaken off from the chain 5. These knives are numbered 30 and 31 and areeach bolted to an angle plate 32 and 33, respectively, which arepivotally mounted on opposite ends of the shaft 8, being spaced from theidler roller 7 by spacer washers 34. As shown the idler roller has abearing plate on each side and the two adjustable plates 21 and 22 haveeach an outward bend beyond the end of the beam 3 which increases theirspread sufficiently to receive the idler roller with its bearing platesbetween them. The spacer washers 34 are between these adjustable platesand the angle plates 32 and 33.

These angle plates and the flaring knives carried by them are oscillatedby a chain drivencrank and connecting arm mechanism which will now bedescribed.

Bearing in upstanding brackets 35 and 36 on the beam 3 some distancefrom its rear end is a sprocket 37. Fastened on the hub of the sprocketon the outer sides of the brackets are crank discs 38 and 39,respectively, each having an eccentric crank pin 40 and 41,respectively, to which are pivoted connecting links 42 and 43,respectively. These connecting links are pivotally connected at theirlower ends with the forward ends of connecting arms 44 and 45,respectively, the rear ends of which arms are connected, as by welding,to the angle plates 32 and r 33, respectively. Therefore the rotation ofthe crank discs raises and lowers the forward ends of the arms 44 and 45and oscillates the flaring knives on their pivots as indicated by thebroken lines in Fig. 2. The sprocket 37 meshes with andis driven by thechain 5.

The flaring knives have a circular cut-out on their rear edges and aninward extension 46 on their rear edges at the bottom. These extensionsare deflectors to cut the bottom of the ditch smooth and to direct theearth cut out by the flaring knives into the scooping path "a of theouter knives 29.

Thus it is apparent that as the trailer is drawn along by the tractor,the knives carried by the chain will be removing the earth along theinclined surface marked X in'Fig. 1 to the full width of the wallportion 47 of the trench and foundation, and that the flaring knivesmeanwhile by their oscillation cut out the flaring sides 48 to thebottom of the trench, the deflector fingers 46 directing the earthremoved by the flaring knives into the path of the knives 29. Thus thetrench of the proper width and with the broader base is dug by onecontinuous operation, constituting a form ready to receive the concretewhich when poured forms a foundation asindicated in Fig. 5.

As shown in Fig. 1 the screw scrapers are above the level of the ground.Their height will depend upon the character of the job and whether'it isnecessary to remove all the dirt from the sides of the trench. Theiradjustment lengthwise of the beam determines their relation to theground level in the operating position of the boom.

It Will be understood that the boom first digs itself down to thedesired depth for the trench, the initial end wall being arcuate with aflare at the bottom on each side and then will continue at uniform depthfor the desired length, when the boom will be raised and the portionwith the inclined bottom beyond the uniform depth portion of thefinished trench will ordinarily be filled in. This of course avoids thenecessity of digging a trench in the first instance of the full width ofthe base and using removable forms for the wall portion and laterfilling in outside of the wall portion.

While a specific construction has been illustrated and described foraccomplishing the desires purpose, it will be understood that this isillustrative merely and that the invention may be otherwise embodied aswill readily occur to those skilled in the art within the scope of theinvention as defined in the following claims.

What is claimed is:

1. A trenching mechanism comprising in combination with tractor powermechanism having rear attaching means, a beam pivoted at one end to therear attaching means of the tractor and having its other end free, asupporting roller pivotally mounted upon the beam near each end thereof,a chain running over the rollers and driven by the power mechanism,scooping means carried by the chain and operative to excavate a trench,a pair of outwardly flaring cutting knives, one knife being pivotallymounted on each side of the free end of the beam, each knife having aforwardly directed cutting edge intersecting the plane of therespectively adjacent side wall of the trench excavated by the scoopingmeans and extending obliquely outwardly and downwardly beyond said sidewall to the plane of the bottom of said trench, an eccentric carried bythe boom and operatively related to the chain, crank means carried bythe boom and operated by the chain, and connecting means between thecrank means and the knives and operative to oscillate the knives.

2. A trenching mechanism as defined in claim 1 in which the flaringknives have inwardly curved bottom portions trailing said cutting edgesfor directing the dirt loosened by the knives into the path of thescooping means.

3. A trenching mechanism as defined in claim 1 in which the crankoperating means for eachknife comprises a sprocket supported in bearingson the beam intermediate its ends and operatively engaging the chain, acrank on the sprocket, and a connecting lever arm between the crank andknife operative to oscillate the knife.

References Cited in the file of this patent UNITED STATES PATENTS844,959 Rockford Feb. 19, 1907 1,214,410 Bauer Jan. 30, 1917 1,400,712Bager Dec. 20,1921 1,411,018 Hammen Mar. 28, 1922 1,684,869 KruegerSept. 18, 1928 1,858,727 Bentson May 17, 1932 2,519,077 Schmidt Aug. 15,1950

